Oxidative Phosphorylation Flashcards
Why is oxygen needed in energy generation
Acceptor electrons and H from the electron transport chain
Allows electrons to constantly move down to generate energy for proton movement for atp synthesis
How does electron movement down transport chain cause proton movement to intermembrane
Movement is exergonic (releases free energy)
This energy is used to move protons through the electron carriers (as channels)
= create a proton motive force for atp generation
What is the energy generated from electrons called
Electron motive force
What 2 factors allow proton motive force to be maintained (to move protons into ATPase
Ph gradient (low ph and high electrical potential in intermembrane)
Explain the structure of the mitochondria and why it’s important in oxidative phosphorylation
Double membrane
Outer membrane
Intermembrane space
Inner membrane (cristae)
Matrix
Inner membrane is folded to allow many ATPase and ETC to generate more atp
What is the first electron carrier protein in the chain which allows the acceptance of 2 e/H from NADH to FMN
NADH oxidoreductase
What does NADH oxidoreductase do (how electrons move to ubiquinone Q)
It transfers the 2 electrons from NADH to FMN
FMN2 (reduced) transfers the electrons
To FeS clusters
Electrons from FeS clusters then transferred to Q
Ubiquinone is then reduced = QH2
What is ubiquinone called when reduced by the electrons from Fe s clusters
Ubiquinol (alcohol formed)
What are FeS clusters
Fe associated with cysteine amino acids SH(thiol)
What does FMN mean and it’s job
Flavin mono nucleotide
It accepts electrons from NADH to be reduced
What is the result of the movement of electrons in the NADH oxidoreductase complex
4 protons are transported into intermembrane
Further 2 are removed from matrix to reduce ubiquinone (QH2)
Net removal - 6 H+
What are the protons which are not transported to intermembrane but removed from matrix called
Chemical protons
What happens with reduced ubiquinol (2 e and 2H)
It is oxidised when the electrons move to cytochrome c oxidoreductase complex
Cytochrome c oxidoreductase becomes reductase (accepts 2E and 2H)
What is the consequence of the reduction of the cytochrome c oxidoreductase complex by Q
Q is oxidised and recycled back to accept more protons
The electron movement in the oxidoreductase complex causes extra 4H+ pumped out
2H+ removed from matrix completely
Net loss in matrix = -6H
Which shuttle molecule accepts 2 electrons from the cytochrome c reductase complex
Cytochrome c shuttle protein
Is ubiquinone a shuttle molecule?
Yes, it always stays in membrane (hydrophobic)
What type of prosthetic group allows cytochrome c to accept 1 electron at a time from cytochrome reductase
C type haem (contains Fe)
Why are 2 ubiquinols (QH2) needed for cytochrome c shuttle protein to accept 2 electrons
Because can only accept 1 at a time
What is the oxidation and reduction of Q called
The Q cycle
What occurs once cytochrome c accepts electrons from cytochrome c reductase complex
Cytochrome c oxidase catalyses the transfer of electrons and protons from the cytochrome c to O2
4e from cytochrome c and 4H+ from the matrix reduce 02 into H20
What does reduction of water by 4 e and 4 h generate
Water and exergonic so power to pump 4 more H+ into intermembrane
What is the net loss in the cytochrome c oxidase complex
8 H+
4 are pumped out due to o2 reduction, 4 are used to reduce water
What is the net loss of H+ in the matrix compared to net gain of H+ in the intermembrane
Intermembrane = 12H+
Matrix = -16 H
What are the 4 complexes in oxidative phosphorylation
I = NADH - Q oxidoreductase complex
II= succinate dehydrogenase- Q complex
III= Q - cytochrome oxidoreductase complex
IV= cytochrome c oxidase complex
How is FADH2 electrons transported to Q ubiquinone (complex II)
Accepted by succinate dehydrogenase which transports the 2E to ubiquinone which is then reduced into ubiquinol
What ion is needed by succinate dehydrogenase to accept electrons from FADH2
Fe (just like NADH oxidoreductase needs it and also cytochrome c has fe)
How does H from the intermembrane space get into ATPase enzyme complex (V)
H half channel which is on the intermembrane side of the ATPase
What happens when H goes into the ATPase half channel
Proton binds to the aspartate (-ve) amino acid on the c ring subunits
This causes the c ring subunit aspartate to become neutral and move into the membrane
(Rotation)
Causing next c ring subunit to be exposed which allows New H to attach
This movement drives rotation
After c ring rotation protons are released through the other half channel and aspartate returns to be negative
What does rotation of the c ring cause to rotate (due to addition of H to make aspartate negative)
Gamma arm which attaches the c ring with beta and alpha proteins on the other side of ATPase
What happens when the gamma Y arm rotates when c ring rotates
Causes rotation of the beta and alpha subunits
Which out of the beta and alpha proteins on ATPase is bigger
Beta
What is attached to beta and alpha apart from the gamma Y arm
B arm
What causes beta arms to move in and out
When beta protein goes past it b arm is pushed out
When alpha goes past b arm when Y rotates this causes b arm to move in
What does b arm movement in and out cause
Kinetic energy which is turned into atp synthesis Adp + pi into atp
At the end of oxidative phosphorylation along with glycolysis and Krebs how many ATP and O2 and H20 produced (6 cycles for glucose)
ATP = 30 generated
6 O2 are used
6 H2O are generated
How many NADH and FADH are present in oxidative phosphorylation
10 NADH (4 from glycolysis , 6 from citric cycle)
2 FADH2 from citric cycle
Which 3 chemicals can prevent oxidative phosphorylation
Carbon monoxide
Cyanide
Salicylate
How can carbon monoxide stop oxidative phosphorylation
Has high affinity to haemoglobin and binds to FE causing no oxygen into cells
How does cyanide stop oxidative phosphorylation
Binding to complex 4 (cytochrome c oxidase )
How can salicylate stop oxidative phosphorylation
Forms pores in membrane so H can move without generating ATP
Why is oxidative phosphorylation damaging to the mitochondria
Etc oxygen species are reactive and can cause high mutation and error rate in dna of mitochondria
What is the difference between cytochrome c coenzyme and ubiquinone Q
Q can carry 2 e and 2 H
Cytochrome c only carries 1 via the haem group
